冷泉羽状流地震波场频谱特征与气含量关系研究

为深入研究羽状流地震响应特征以及羽状流气含量反演,利用实际羽状流地震偏移剖面中单道和多道地震数据,首先进行地震波时域波形特征分析以及地震波场频谱特征分析,羽状流时域波形呈现出散射波动特征,其频谱较宽,表现出开叉较多的散射波频谱特征。然后通过已有气含量与振幅属性关系模型反演气含量,提取羽状流地震频谱参量。最后进行羽状流地震频谱参量与气含量的相关性分析,结果表明:气含量改变时会引起各频谱参量的变化,羽状流各频谱参量(除优势频宽)均与气含量呈现出较好的正相关关系,其中总能量和有限带宽能量的相关性曲线拟合程度最佳;主频和振幅谱最大值分布较散,但其拟合结果仍然呈现正相关趋势;优势频宽与气含量表现出负相关趋势。以上获得的羽状流地震信号时域波形特征、地震波场频谱特征及频谱参量与气含量的关系,为羽状流的地震探测以及气含量反演奠定了基础。

Study on the Relationship Between Spectral Characteristics of Seismic Wave Field and Gas Content of Plume in Cold Seepage

To study the seismic response characteristics of plume and inversion of gas content in plume, we used the single- and multi-channel seismic data in seismic migration profile of the actual plume to firstly analyze the time-domain seismic waveform characteristics and the seismic wave field spectral characteristics. The plume time-domain waveform shows scattering features and wide spectrum, showing the characteristics of scattering wave with more forks. Gas content was inversed through the existing relation model of gas content and amplitude attribute, and the plume seismic spectral parameters were extracted. Finally, the correlation between the plume seismic spectral parameters and gas content was analyzed. The results show that the gas content variation would change each of the spectral parameter, and all the spectral parameters (except dominant bandwidth) are positively correlated with the gas content, and the correlation curves of total energy and limited bandwidth energy have the best fitting. Distribution of the dominant frequency and the maximum amplitude spectrum is scattered, but the fitting results still show a positive correlation trend. Negative correlation is presented between the dominant bandwidth and the gas content. The time-domain waveform characteristics, seismic wave field spectral characteristics, and the relationship between seismic signal spectral parameters and plume gas content strengthens the foundation for seismic detection and gas content inversion of plume.